A
C
D
A
B
D
A
C
B
D
A
B
A
D
A
C
B
D
A
B
D
C
B
A
C
B
C
D
C
B
B
D
A
C
B
D
A
C
B
A
C
B
D
A
C
D
C
B
C
D
A
C
D
A
D
1